add "monitor" build target for idf

Kconfig

 menu "Arduino Configuration"
 
+choice MONITOR_BAUD
+    prompt "Monitor baud rate"
+    default MONITOR_BAUD_115200B
+    help
+        Baud rate to use while monitoring the ESP chip.
+
+config MONITOR_BAUD_9600B
+    bool "9600 bps"
+config MONITOR_BAUD_57600B
+    bool "57600 bps"
+config MONITOR_BAUD_115200B
+    bool "115200 bps"
+config MONITOR_BAUD_230400B
+    bool "230400 bps"
+config MONITOR_BAUD_921600B
+    bool "921600 bps"
+config MONITOR_BAUD_2MB
+    bool "2 Mbps"
+config MONITOR_BAUD_OTHER
+    bool "Custom baud rate"
+
+endchoice
+
+config MONITOR_BAUD_OTHER_VAL
+    int "Custom baud rate value" if MONITOR_BAUD_OTHER
+    default 115200
+
+config MONITOR_BAUD
+    int
+    default 9600 if MONITOR_BAUD_9600B
+    default 57600 if MONITOR_BAUD_57600B
+    default 115200 if MONITOR_BAUD_115200B
+    default 230400 if MONITOR_BAUD_230400B
+    default 921600 if MONITOR_BAUD_921600B
+    default 2000000 if MONITOR_BAUD_2MB
+    default MONITOR_BAUD_OTHER_VAL if MONITOR_BAUD_OTHER
+
 config AUTOSTART_ARDUINO
     bool "Autostart Arduino setup and loop on boot"
     default "n"

Makefile.projbuild

+#build with "make flash monitor" to upload and open serial monitor
+monitor:
+	$(Q) miniterm.py --rts 0 --dtr 0 --raw $(ESPPORT) $(CONFIG_MONITOR_BAUD)